A pick and place apparatus is used to pick up an object from a first location and thereafter to place the object in a second location. Pick and place apparatus are typically used in various semiconductor manufacturing processes, such as die bonding and die sorting.
After a semiconductor wafer has been fabricated, the semiconductor wafer is usually mounted onto an adhesive film such as Mylar film. The semiconductor wafer is subsequently singulated into individual semiconductor dice. Then, a pick and place apparatus may be used to pick a die from the adhesive film, and transfer the die to a desired location.
The speed of a pick and place operation, for example a die attachment operation, is partly dependent on the speed with which the pick and place apparatus can function to accurately pick a die and place the die in the desired location. However, as die sizes continue to shrink, greater accuracy is required during pick and place operations. As a result, the competing needs for speed and accuracy pose challenges for pick and place apparatus.
FIG. 1 is a perspective view of a pick arm 12 for a pick and place apparatus 10 according to the prior art. The pick and place apparatus 10 comprises the pick arm 12 rotatable about a rotary axis 18 of an actuator 16. A pick tool 14 is located near a distal end 15 of the pick arm 12. The pick arm 12 rotates to a pick-up location, where singulated dice adhering to an adhesive film are positioned below the pick tool 14 and the pick arm 12. A die to be picked up is positioned below the pick tool 14. The pick arm 12 moves downwards along the Z axis, for the pick tool 14 to pick up the die. After picking up the die, the pick arm 12 moves upwards along the Z axis, and then rotates along a transfer plane to a placement location. The desired location to place the die is positioned below the pick tool 14 and the pick arm 12 at the placement location.
In high speed pick and place operations, the pick arm 12 is rotated about the rotary axis 18 at high speeds, and is stopped at the pick-up location or the placement location rapidly. These rapid movements of the pick arm 12 create air turbulence and/or air pressure differences in the air above the adhesive film, thus causing the adhesive film, at the pick-up location or the placement location, to vibrate uncontrollably. The adhesive film may vibrate to such an extent that the dice on the adhesive film hit the pick tool 14, which may damage the dice. Moreover, even if the dice do not hit the pick tool 14, the pick tool 14 cannot proceed to pick or place the die until the adhesive film stops its vibration. This slows down the pick and place operations, and therefore reduces throughput.